<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="../js/jquery-3.5.1.js"></script>
</head>
<body>
<h1 id="title">你是人间四月天</h1>
<script type="text/javascript">

     var jql = $("#title"); //jQuery对象  默认隐式迭代 都是数组
    // jql.css("color","red");
     //jQuery对象[n] = DOM对象
     //jQuery对象.get(n) = DOM对象
     jql.get(0).style.color = "red";

    // var dom = document.getElementById("title");//DOM对象
    // dom.style.color = "red";
    // $(dom).css("color","red");//$(DOM对象) = jQuery对象

</script>
</body>
</html>